PubMed · 4025607
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M Ostow. 1985. Blinking frequency and dopamine availability.. https://doi.org/10.1176/ajp.142.8.994a
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In order to assess the clinical utility of trigemino-facial reflexes in lower facial muscles, we studied perioral reflexes to mechanical and electrical stimulation in 13 patients with spasmodic dysphonia and orofacial dyskinesia and in 7 healthy subjects. Mechanical stimulation of the upper lip of all patients and electrical stimulation of the infraorbital nerve of patients with orofacial dyskinesia elicited larger perioral reflexes than in controls. In the majority of patients, hyperexcitable perioral reflexes were accompanied by increased gain of the blink reflex. In 4 patients, however, trigemino-facial reflexes were enhanced selectively in either the perioral muscles or orbicularis oculi. Our findings suggest that the quantitative assessment of perioral reflexes may provide information about the excitability of brainstem interneurons in cranial dystonia that is complementary to blink reflex studies.
The "recognition potential" is an electrical response of the brain that occurs for recognizable, but not for non-recognizable, images. When a recognizable image evokes it, the more rostral of a pair of vertically oriented occipital electrodes reaches an initial positive peak at about 200-250 msec. Several properties distinguish this component of the evoked response from event-related potentials such as N2 or P3. A new method of stimulation was devised that evoked the recognition potential for recognizable images, but virtually no response of any kind for non-recognizable images. This was accomplished by presenting images at high rates. Chinese ideographs evoked it for subjects whose native language was Chinese, but not for subjects unfamiliar with that language. This showed that the recognition potential was not caused by differences in the physical attributes of the images per se. Instead, recognizability, as defined by a subject's individual learning experience, was the important factor.
BACKGROUND: The role of the lacrimal sac in the lacrimal pump mechanism is controversial. METHODS: Movements of the lateral wall of the lacrimal sac with blinking were videotaped through an endoscope in eight patients after dacryocystorhinostomy. In addition, movements of an air bubble at the opening of the nasolacrimal duct with blinking were studied in three patients with an incompetent valve of Hasner. RESULTS: The superior half of the lateral wall of the lacrimal sac moved laterally with lid closure and medially with lid opening. The inferior half of the lateral wall of the lacrimal sac moved medially with lid closure and laterally with lid opening. In patients with an incompetent valve of Hasner, the air bubble at the opening of the nasolacrimal duct bulged into the nose with lid closure and retracted into the nasolacrimal duct with lid opening. CONCLUSIONS: A tricompartment model of the lacrimal pump is presented that incorporates these findings. With lid closure, the orbicularis muscle contracts, compressing the canaliculi and pulling the superior half of the lateral wall of the lacrimal sac laterally. This creates a lower pressure in the superior sac, allowing tears to be propelled from the canaliculi into the sac. At the same time, the inferior half of the lateral sac wall moves medially, creating a positive pressure in the inferior sac and nasolacrimal duct, thus forcing tears down the duct into the nose. With lid opening, the orbicularis muscle relaxes, allowing the canaliculi to open and the superior half of the lateral sac wall to move medially. The resulting negative intracanalicular pressure allows tears to flow from the lacrimal lake into the canaliculi, and the higher pressure in the superior sac closes the valve of Rosenmueller and forces tears from the superior to inferior sac and proximal nasolacrimal duct. At the same time, the inferior half of the lateral sac wall moves laterally, resulting in a negative pressure in the inferior sac and nasolacrimal duct.